In recent years, various types of miniature portable electronic devices such as electronic watches, electronic calculators, etc, have come into widespread use. In the case of electronic calculators, the normal arrangement used for input of data such as numerals and symbols is to provide a conventional type of keyboard made up of an number of pushbutton switches, with each switch being used to input a particular numeral, character or symbol. Such an arrangement is convenient for use with a device which is reasonable large in size. However, in the case of a device which is of very small size, such as an electronic wristwatch, the size of the keys and the keyboard must be made extremely small, making the input of data to such a device highly inconvenient. There is therefore a requirement at present for some means of inputting data to a miniature electronic device such as an electronic wristwatch which will not require the use of a keyboard and pushbutton switches, and which will be easy and convenient to use. With the availability of such input means, in conjunction with recent advances in integrated circuit technology, various new facilities could be provided such as, for example, a list of names, telephone numbers, addresses, etc., stored in an electronic wristwatch and easily accessed by the wearer when desired.
The present invention discloses such input means, overcoming the problems of prior art input means such as pushbutton keyboards discussed above. With an input device according to the present invention, a user can input data in the form of patterns representing numerals, characters or symbols, simply by tracing out the shape of each pattern over an array of sensor elements such as touch-sensitive switch electrodes. These sensor elements can conveniently be arrayed over a display surface of the device into which data is input, so that the user can immediately confirm correct input of each pattern, so that for example the sensor elements could be arranged on the upper surface of the watch glass of an electronic wristwatch. It is a particular feature of the present invention that the data input from the sensor elements is interpreted in such a way that only a small number of sensor elements can be used to represent a very large number of different patterns.